In Search of Lost Time [volumes 1 to 7]

by Marcel Proust

A vicious person, always affecting the same air of virtue before people whom he is anxious to keep from having any suspicion of his vices, has no register, no gauge at hand from which he may ascertain bow far those vices (their continuous growth being imperceptible by himself) have gradually segregated him from the normal ways of life.

Oh Swann jealousy is such a cancer